Do I ever ask a question that isn't a setup? (Ok, sometimes I'm just curious, but I usually say that when it happens.)
This is not scientific. Those zygotes are human. They may not become a viable embryo, but that does not make them non-homo sapien. They do not become nothing.
Clearly, some things are beyond human control. Does every zygote have the right to be born? If only that were within our technology - many a couple struggling with infertility would have hope.
Rather, it is one of opportunity. Should every zygote deserve an opportunity to develop? If a zygote develops to a viable embryo, what then?
Perhaps most importantly, shouldn't there be a principled reason for a societal decision where to draw the lines?
Personally, it looks like technology is moving forward dramatically. It is not beyond the realm of possibility to say that we might be able to determine fetal viability in individual cases with a high level of confidence. The Supreme Court did not have that when it decided Roe v. Wade. I think that's an important time-stamp. Once an embryo is viable, it is a life separate from the mother in legally meaningful ways.
You were the kid knocking on this door weren't you?